6. Scale Model of the Earth’s Interior

Objective:

Students will gain a better understanding of the Earth’s interior structure through the use of a scale model.

Procedure:

Approximate the relative sizes of the Earth’s interior layers, and then build a scale model of the Earth’s interior on a 7-meter-long sheet of paper (scale of 1 mm = 1 km). Follow the procedure outlined below.

Using a meter stick, cut a section of rolled paper measuring 7 meters in length. The goal of this activity is to estimate the relative thickness of the Earth’s layers on this sheet of paper.

Neatly write “Center of the Earth” on one end of the paper, and draw a line to indicate where the Earth’s center is.

Based on your current knowledge of the Earth’s layers (using the scale of 1 mm = 1 km), put markings on the paper where you think each layer of the Earth begins and ends (and label these markings). Include: the inner core, the outer core, the mantle, the crust, the lithosphere, and the Earth’s surface. Also include (and label) markings for the top and bottom of the Earth’s biosphere (livable area)*.

At the surface of the model (which represents the Earth’s surface) draw how high you think the world’s tallest mountain (Mt. Everest) would be if drawn to scale. Do the same for the deepest part of the ocean.

Calculate the actual relative thicknesses and depths of the Earth’s layers using the information provided by your teacher as a guide, and the scale of 1 mm = 1 km. Using a second color, indicate (and label) where each layer of the Earth begins and ends. Also include (and label) markings for the top and bottom of the Earth’s biosphere, and draw how high the world’s tallest mountain (Mt. Everest) and the deepest part of the ocean would be to scale.

Label each layer and include the following information for each:

Thickness of the layer

Approximate temperature within that layer

Composition of the layer

Phase of material in the layer (solid or liquid)

Feel free to be creative with color and design.

Reflections:

1. Describe anything that surprised you about the scale model and layers of the Earth’s interior.

2. In what way did this lab help you to visualize the scale of Earth’s interior? What did you learn from this activity that you did not previously know?

3. If the deep interior of the Earth can’t be seen, how did scientists determine the structure of the Earth’s interior?

4. If we haven’t “been there”, do we really know what’s down there? What does it mean to “know” something if we can’t actually “touch” it? Is this the same kind of knowledge as when we say that we know that there is a planet orbiting a distant star? Is it the same as when a doctor takes an x-ray, and therefore “knows” that there is some structure inside your body?

5. Can you think of any other reflection questions that would be appropriate for this exercise? If yes, what is your question, and how would you answer it?

Reference:

Based on the “Scaled Earth” poster, developed by Steve Murrie (sciencekit.com).

* Life forms that we are familair with on Earth exist within the biosphere, a thin layer extending down into the upper few km of the Earth’s crust and up to about 10 km into the atmosphere. This thin layer of life is supported by the internal layers of the Earth and is surrounded by the vast expanse of space surrounding the Earth.